radon vent pipe 5

https://wiki-site.win/index.php/Understanding_Radon_Mitigation_Cost_for_Your_West_County_Home

You might see a radon vent pipe poking up from the ground next to a house, especially during construction. It's not the prettiest thing, but that pipe is actually a lifesaver—it pulls dangerous radon gas from the soil under the slab and vents it safely into the air above the roof, keeping the indoor air clean.